win: support x64 reading x86 (wow64)

snapshot/win/exception_snapshot_win.h

Index: snapshot/win/exception_snapshot_win.h
diff --git a/snapshot/win/exception_snapshot_win.h b/snapshot/win/exception_snapshot_win.h
index 277cd4a5117eb23ddea04d1f6926245cb34441fa..e5dc1fa777a8eae68b67fc01e527225486352880 100644
--- a/snapshot/win/exception_snapshot_win.h
+++ b/snapshot/win/exception_snapshot_win.h
@@ -24,6 +24,7 @@
 #include "snapshot/exception_snapshot.h"
 #include "util/misc/initialization_state_dcheck.h"
 #include "util/win/address_types.h"
+#include "util/win/process_structs.h"
 
 namespace crashpad {
 
@@ -61,12 +62,25 @@ class ExceptionSnapshotWin final : public ExceptionSnapshot {
   const std::vector<uint64_t>& Codes() const override;
 
  private:
-  template <class ExceptionRecordType, class ContextType>
+  template <class ExceptionRecordType,
+            class ExceptionPointersType,
+            class ContextType>
   bool InitializeFromExceptionPointers(
       const ProcessReaderWin& process_reader,
-      const EXCEPTION_POINTERS& exception_pointers,
+      const ExceptionPointersType& exception_pointers,
       ContextType* context_record);
 
+  template <class ContextRecordType>
+  bool CommonX86Initialize(
+      const ProcessReaderWin& process_reader,
+      const process_types::EXCEPTION_POINTERS<
+          process_types::internal::Traits32>& exception_pointers);
+
+  template <class ExceptionPointersType>
+  bool ReadExceptionPointers(const ProcessReaderWin& process_reader,
+                             WinVMAddress exception_pointers_address,
+                             ExceptionPointersType* exception_pointers);
+
 #if defined(ARCH_CPU_X86_FAMILY)
   union {
     CPUContextX86 x86;